1. Field of the Invention
This invention relates to the addition reaction type of organopolysiloxane compositions. More precisely, this invention provides organopolysiloxane compositions which can be stored in a one-package form for a long time in a stable state by covering an organohydrogenpolysiloxane which is a cross-linking agent with a nonpermeable film, and which can be cured by breaking this nonpermeable film at the time of application.
2. Description of the Prior Art
The addition reaction type of organopolysiloxane compositions have the characteristics that no reaction by-products are produced during curing and that curing proceeds uniformly and quickly in thick sections. For example, they have been widely utilized as bonding agents, potting materials and coating materials for electrical and electronic devices, molding materials, peelable coating materials for paper and films, and fiber treatment agents.
However, when an organopolysiloxane composition of the addition reaction type is prepared in one package containing all the indispensable components, storage stability is lost within a short period. Thus, there is the problem that a one-package form essentially cannot be prepared. As a result, all the indispensable components must be divided into two or three packages, or the components must be mixed immediately before use. In this case, there are the disadvantages of measuring the various components, of complicated mixing procedures and of limited pot life.
Catalyst systems for the addition reaction have been conventionally used to overcome these drawbacks. In particular, an attempt has been made to inhibit the catalytic activity of a platinum catalyst by including another additive. The following compounds have been proposed as additives for inhibiting this reaction: benzotriazole in U.S. Pat. No. 3,192,181, thiourea derivatives in British Patent Specification No. 1,054,658, acetylene derivatives in U.S. Pat. No. 3,445,420, acrylonitrile derivatives in U.S. Pat. No. 3,344,111, tetramethylguanidine carboxylate derivatives in U.S. Pat. No. 3,461,185, sulfoxide derivatives in U.S. Pat. No. 3,453,234 and halocarbon derivatives in U.S. Pat. No. 3,383,356. However, since the platinum catalyst has a strong catalytic activity, it is difficult to inhibit the catalytic function of the catalyst completely by using an additive. Therefore, the use of an additive for inhibiting catalytic activity is insufficient to allow the production of an addition reaction type of organopolysiloxane composition in a one-package form.
The inventor continued investigations to overcome the above-mentioned drawbacks. As a result, it was found that the organopolysiloxane of the addition reaction type can be prepared in a one-package form with excellent storage stability on the basis of a method which is essentially different from the above-mentioned method.